Disazo dyestuff and its production



Patented Feb. 25, 1936 UNITED STATES PATENT OFFICE DISAZO DYESTUFF ANDITS PRODUCTION Adolf Krebser, Basel, Switzerland, assignor to the firmJ. R. Geigy A. G., Basel, Switzerland No Drawing. Application March 20,1935, Serial No. 12,108. In Germany April 12, 1934 2 Claims. (Cl. 26077)This invention relates to the manufacture of prising; there is nothingin literature or in techdisazo dyestufis by coupling a tetrazotizeddinical knowledge which would lead one to suppose amino base accordingto the following general that the difference might exist. formula: Thefollowing example illustrates the inven- H2NR,SR NH2 tion: 5

21.6 kilos of thio-aniline (4,4'-diamino-diwherein R is an aromaticresidue, with a para phenyl-sulphide) are tetrazotized in the usualsubstituted phenol capable of being coupled and manner and the productis coupled in solution containing no sulphonic or carboxylic group, soalkaline with sodium carbonate with 21.6 kilos as to form a disazodyestuff. The new dyestuifs of 4-hydroxy-1-methylbenzene. Theyellow-orthus obtained are very suitable for dyeing celluange powderthus produced dissolves in concenlose ester lacquers, spirit lacquers,oils and fats trated sulphuric acid to a brown-red solution w and alsofor use in the graphic arts, for instance, and dyes mixtures ofnitro-cellulose and acetylcopper-block printing. cellulose and themixtures of resins and solvents The U. S. Patent No. 1,819,957 disclosesthe use used in copper-block printing pure yellow tints. of similardyestuffs from diamino bases of the di- The solubility in these mixturesis remarkable; or tri-arylmethane series and amines and phethe depth ofcolor is nearly double that of the nols capable of being coupled fordyeing fats already known dyestuifs, for example, those of and oils. Ascompared with the older dyestuffs U. S. Patent No. 1,819,957. for fatsthese dyestufis are distinguished by the What I claim is:-- fac tha t yhave new Properties ch, for 1. A process for the manufacture of a disazoth fi s m ma s it possible t use y s s dyestufi, insoluble in water,consisting in couof this kind for graphic purposes, for example, inpling tetr-azotized thio-aniline with 4-hydroxyproducing two-tone colorsin copper-block printl-methylbenzene.

ing. 2. Disazo dyestuff, insoluble in water, of the 5 When, however, inaccordance with the present following formula,

invention, the -CH2 or CHR group in the diamino base of the aforesaidpatent is replaced N=N- s-C -N=N by sulphur as mono-atomic link memberfor uniting the two aromatic bases, there are ob- 0H OH tained bytetrazotizing and coupling with parasubstituted phenols disazo dyestuffsinsoluble in CH: CH

water which are distinguished by very good solubility in the solventsand varnish mixtures used said dyestufi having a great coloring powerand in the graphic art and are differentiated from a good fastness tolight and being suitable for the known dyestufis by a much betterfastness dyeing cellulose ester lacquers, spirit lacquers, to light andby a considerably greater coloring oils and fats and also for use in thegraphic arts. power. This diiference in coloring power is sur- ADOLFKREBSER.

